Energy suppliers may request users to suppress the usage of energy so that the amount of energy can be adjusted in the users' equipment for the purpose of improvement of efficiency of existing energy supply equipment, stable supply, of energy, global environment protection, and the like.
For example, Japanese Laid-open Patent Application No. 2005-107901 proposes a system in which the power is adjusted by suspending users' equipment based on needs of the power supplier and according to a priority order concerning the suspension of the equipment established in advance by the users upon request of a power supplier due to the tight supply-demand balance of the electric power.